This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Chronic obstructive pulmonary disease (COPD) in the United States annually kills nearly 125,000 people and costs this country $37.2 billion. Cigarette smoking accounts for 80[unreadable]90% of all cases of COPD. Cigarette smoke rapidly increases the permeability of airway epithelium, especially in those with COPD. The barrier function of an intact epithelium is maintained by tight junctions between adjacent cells. Little is known about the mechanisms underlying tight junction function in respiratory epithelium. Our long-range goal is to define the mechanisms responsible for cigarette smoke induced alterations in lung epithelial cell function in order to develop effective therapeutic strategies to inhibit this altered function. The objective of this proposal is to establish the mechanism by which fresh, whole cigarette smoke from market relevant cigarettes regulates the activity of Rho GTPase in human lung epithelial cells. The central hypothesis of this proposal is that smoke from market relevant cigarettes activates Rho through the combined regulation of both a guanine nucleotide exchange factor (GEF) and a GTPase activating protein (GAP). The rationale for this proposal is that identifying the activators of Rho will allow mechanisms that control lung epithelial cell function to be defined, resulting in the identification of potential targets for therapeutic interventions. The central hypothesis will be tested and the objective accomplished through two specific aims: 1) determine the extent to which a RhoGEF contributes to the reversible activation of Rho in human lung epithelial cells exposed to cigarette smoke;2) determine the extent to which a RhoGAP contributes to the reversible activation of Rho in human lung epithelial cells exposed to cigarette smoke. The proposed work is innovative because it builds on a recently developed technique to expose lung epithelial cells in vitro under conditions that mimic the exposure conditions within the in vivo lung. Our expectation is that this approach will establish that the RhoGEF, GEF-H1, and the RhoGAP, DCL-1, through there regulation of Rho contribute to the cigarette smoke induced loss of barrier function. The outcome is significant because it will define the signal transduction pathways that regulate Rho activation in lung epithelium exposed to cigarette smoke, and will provide insights for the development of strategies to control the loss of epithelial integrity. The proposed study fulfills the INBRE program objectives to increase biomedical research capacity within the Alaska INBRE network, to engage students in the research endeavor and to improve the research environment at a primarily undergraduate partner institution.